This invention relates generally to turbine components, and more particularly, to components for gas turbine engines and methods of fabricating the same.
Known compressors for use with gas turbine engines include multiple stages or rows of rotor blades and corresponding stator vanes which sequentially increase the pressure of the air flowing therethrough. At least some known compressor rotor blades include airfoils that are integrally formed with a perimeter of a rotor disk in a unitary blisk configuration. However, because the blisk airfoils are integrally formed with the supporting rotor disk, the airfoils are not individually removable or replaceable in the event of foreign object damage (FOD) thereof. More specifically, during operation of a gas turbine engine, a blisk rotating therein may be subject to foreign object damage if foreign objects are ingested into the engine. Such foreign object damage may affect blisk airfoil leading and trailing edges.
In some cases, when the damage to such blisks is only relatively minor, the damage may be simply removed, by grinding for example, thus sizing the airfoil with a less than original configuration. However, such repair techniques may be unacceptable if the repair will cause the aerodynamic performance of the blisk to be degraded, and/or cause rotor imbalance. Furthermore, damage removal may adversely affect strength of the airfoil itself.
During manufacturing of a blisk, the material of the blisk is selected based on a number of loading and environmental considerations. Accordingly, impact and wear resistance of the blisk airfoil edges are not the only design considerations, and as such, the material selected may be a compromise optimized for all performance requirements and not just selected to facilitate maximizing edge impact and wear resistance. As such, at least some known blisks are fabricated as bi-alloy components in which a second material is coupled to a blisk forging fabricated from a first material. More specifically, with known blisk manufacturing methods, initially a blisk forging is machined to a semi-finished condition. An edge material is then coupled to the blisk by a fusion welding process. The blisk is then heat-treated and machined to a final configuration. However, such manufacturing methods are generally time-consuming. Moreover, because of the possibility of distortion from the numerous welds and/or the possibility of defects that may be inherent in the fusion welding, such manufacturing methods may not be cost effective.